The overall objectives for the proposed research program are: 1) to establish metabolic relationship among diacylglycerols, phosphatidic acids and diacyl-glycerophosphorylinositols in brain under steady state and stimulated conditions, (2) to examine the different types of acyl transfer processes in brain, (3) to investigate the cyclic nucleotide mediated mechanism of deacylation-reacylation cycle in brain in vivo and (4) to demonstrate the effects of neurotransmitters and psychotropic drugs on brain acyl group metabolism. Special emphasis will be placed on a more detailed study of the acyl group metabolism in brain synaptosomes and subsequent localization of the effects in the subsynaptic components. For in vivo experiments, labeled fatty acid precursors will be injected intracerebrally into mouse brain. Metabolism of the precursors among different lipid components in brain subcellular fractions will be followed with time and compared under various conditions stimulated by neurotransmitters and drugs. For in vitro experiments, labeled phospholipid substrates will be prepared and further incubated with freshly prepared synaptosomes and/or microsomes from brain homogenates. The biochemical properties and kinetics of various types of enzymes utilizing the labeled substrates will be examined. Results of the investigation would yield new and important information regarding metabolism of acyl groups in brain membrane phosphoglycerides and a better understanding of their roles in synaptic transmission as well as other types of brain membrane functions.